quiet the prune testcase

Signed-off-by: Serge Hallyn <serge.hallyn@ubuntu.com>
cgmanager: pass right remove-on-empty flag to prune

Signed-off-by: Serge Hallyn <serge.hallyn@ubuntu.com>
account for premounting sadness in test24

Signed-off-by: Serge Hallyn <serge.hallyn@ubuntu.com>